Add basic standalone debugger test

tests/standalone/debugger/basic_debugger_test.dart

+// Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file.
+
+// This test forks a second vm process that runs this dart script as
+// a debug target.
+// Run this test with option --wire to see the json messages sent
+// between the processes.
+// Run this test with option --verbose to see the stdout and stderr output
+// of the debug target process.
+
+import "debug_lib.dart";
+
+bar(x) {
+  print(x);
+}
+
+foo(i) {
+  bar("baz");
+  print(i);
+}
+
+main() {
+  if (RunScript(testScript)) return;
+  print("Hello from debuggee");
+  foo(42);
+  print("Hello again");
+}
+
+
+// Expected debugger events and commands.
+var testScript = [
+  Breakpoint(),  // Expect a breakpoint event.
+  MatchFrame(0, "main"),  // Top frame in trace is function "main".
+  Step(),
+  Breakpoint(function: "main"),
+  SetBreakpoint(8),  // Set breakpoint a line 15, in function bar.

[siva, 2012/12/19 18:28:58]

Set breakpoint at line 15.....

[hausner, 2012/12/19 22:01:51]

Good catch. The test passed anyway, basically terminating too soon. Added check
to make sure we see all expected debugger events before the shutdown event. 

+  Resume(),
+  Breakpoint(function: "bar"),
+  MatchFrames(["bar", "foo", "main"]),
+  MatchFrame(1, "foo"),
+  Resume(),
+];